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Small Molecule Binding Sites on the Ras:SOS Complex Can Be Exploited for Inhibition of Ras Activation

Lookup NU author(s): Dr Julie Tucker

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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


Abstract

Constitutively active mutant KRas displays a reduced rate of GTP hydrolysis via both intrinsic and GTPase-activating protein-catalyzed mechanisms, resulting in the perpetual activation of Ras pathways. We describe a fragment screening campaign using X-ray crystallography that led to the discovery of three fragment binding sites on the Ras:SOS complex. The identification of tool compounds binding at each of these sites allowed exploration of two new approaches to Ras pathway inhibition by stabilizing or covalently modifying the Ras:SOS complex to prevent the reloading of Ras with GTP. Initially, we identified ligands that bound reversibly to the Ras:SOS complex in two distinct sites, but these compounds were not sufficiently potent inhibitors to validate our stabilization hypothesis. We conclude by demonstrating that covalent modification of Cys118 on Ras leads to a novel mechanism of inhibition of the SOS-mediated interaction between Ras and Raf and is effective at inhibiting the exchange of labeled GDP in both mutant (G12C and G12V) and wild type Ras.


Publication metadata

Author(s): Winter JJ, Anderson M, Blades K, Brassington C, Breeze AL, Chresta C, Embrey K, Fairley G, Faulder P, Finlay MR, Kettle JG, Nowak T, Overman R, Patel SJ, Perkins P, Spadola L, Tart J, Tucker JA, Wrigley G

Publication type: Article

Publication status: Published

Journal: Journal of Medicinal Chemistry

Year: 2015

Volume: 58

Issue: 5

Pages: 2265-2274

Print publication date: 12/03/2015

Online publication date: 19/02/2015

Acceptance date: 19/02/2015

Date deposited: 15/12/2015

ISSN (print): 0022-2623

ISSN (electronic): 1520-4804

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/jm501660t

DOI: 10.1021/jm501660t

PubMed id: 25695162


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